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Old 30th April 2009, 03:10 PM   #1
pat49hk is offline pat49hk  Hong Kong
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Default SEPP output transformer

Dear All,

I found a SEPP circuit from an old magazine of year 1966 as Fig-1 shown. It was using an output transformer which has two groups of primary windings. Can anybody explain what is the different if using a single winding transformer as Fig-2 and the advantages and disadvantages in comparison?

Thanks

Patrick
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Old 30th April 2009, 03:12 PM   #2
pat49hk is offline pat49hk  Hong Kong
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Fig-2
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Old 30th April 2009, 09:44 PM   #3
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Fig. 1 shows 2 windings, each with screen current drawn through it in opposite phase, therefore the DC cancels.

AC wise, it's the same as Fig. 2.

But there's a hair bit of DC in fig. 2 that appears to be some FB method to the driver tube.

Cheers!
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Old 1st May 2009, 10:19 AM   #4
pointy is offline pointy  United Kingdom
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you may be able to get a transformer with a centre tapped primary and then cut at the centre tap so you have the two half's.

(like them diy's would do in thems days)
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Old 2nd May 2009, 01:20 AM   #5
pat49hk is offline pat49hk  Hong Kong
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Dear Geek,

Thank you for your response. Can you tell me more details of the transformer winding topology of both?

Dear Pointy,

Thank you for your advice, I intend to wind the transformer myself. Any idea can tell?

Regards

Patrick
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Old 2nd May 2009, 06:21 AM   #6
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Hi Patrick,

Quote:
Originally posted by pat49hk
Dear Geek,

Thank you for your response. Can you tell me more details of the transformer winding topology of both?
Not any more than I have really... I haven't studied or explored parafeed transformers that much, outside of making a pair for a headphone amp that used neither of these topologies. So I shall derfer to someone who may know more.

Cheers!
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Old 2nd May 2009, 08:34 AM   #7
pat49hk is offline pat49hk  Hong Kong
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Dear Geek,

However, thanks a lot.

Regards

Patrick
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Old 2nd May 2009, 08:45 AM   #8
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Hi Patrick !

I did a similar project.

Click the image to open in full size.

Here are some pics about it.

regards, Simon
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Old 2nd May 2009, 08:57 AM   #9
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That parafeed cap seems very small. When i messed about with parafeed I always used something around 4uf.

What power where you getting?

Looks like one of my messy builds.

Shoog
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Old 2nd May 2009, 06:20 PM   #10
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Default Re: SEPP output transformer

[QUOTE]Originally posted by pat49hk
[B]Dear All,

I found a SEPP circuit from an old magazine of year 1966 as Fig-1 shown. It was using an output transformer which has two groups of primary windings. Can anybody explain what is the different if using a single winding transformer as Fig-2 and the advantages and disadvantages in comparison?

Hi,
Fig1 is right for pentodes fig 2 is only work for triode.the two resistor of g2 will eat most of the output power.
Cheers!
Singh
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